Fixture for heat treating furnaces

ABSTRACT

A fixture for heat treating furnaces is disclosed having a frame composed of upright bars, horizontal and diagonal bars and horizontal rods held is assembled relation by wires, of low fixture mass, the bars, rods and wires preferably being of low specific heat material, and preferably of molybdenum but alternatively of tungsten, tantalum, columbium and their alloys or of graphite, with an associated rack of the same material having horizontal ceramic tubes to support the articles to be heat treated in the furnace.

United States Patent Kreider et al.

1541 FIXTURE FOR HEAT TREATING FURNACES [72] inventors: Benjamin A.Kreider, Richboro; Charles J. Schmidt, Philadelphia; Howard R.Martindell, lvyland, all of Pa.

[73] Assignee: Abar Corporation, Feasterville, Pa.

221 Filed: Feb.16, 1971 211 Appl.No.: 114,937

[52] US. Cl. ..263/47 R [51] Int. Cl ..F27b 21/04 [58] Field of Search.....220/l9; 34/237, 238; 263/47,

[56] References Cited UNITED STATES PATENTS Bixby 14 1 Oct. 17, 1972aziaai i/nza T1111 et at .I.....i63/47 A 3,227,431 1/1966 Steeves..263/48 Primary Examiner-John J. Camby Attorney-Zachary T. Wobensmith[57] ABSTRACT A fixture for heat treating furnaces is disclosed having aframe composed of upright bars, horizontal and diagonal bars andhorizontal rods held is assembled relation by wires, of low fixturemass, the bars, rods and wires preferably being of low specific heatmaterial, and preferably of molybdenum but alternatively of tungsten,tantalum, columbium and their alloys or of graphite, with an associatedrack of the same material having horizontal ceramic tubes to support thearticles to be heat treated in the furnace.

5 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION 1 Field of theInvention This invention relates to fixtures for heat treating furnaces.

2. Description of the Prior Art It has heretofore been proposed toemploy fixtures which were molded or cast of nickel base alloys forsupporting in a heat treating furnace the articles to be heat treated.The fixtures heretofore available had various shortcomings includingrelatively high mass which lengthened and thus adversely affected thecycle time, relatively high specific heat of the metal which alsoadversely affected the cycle time, a tendency to sag and distort withrelatively short life, the necessity for removal during bake-out andclean-up cycle to avoid formation of an eutectic, and lack ofadaptability to work pieces of different sizes and shapes.

The objectionable features of the prior fixtures are overcome with thefixtures of the present invention.

I SUMMARY OF THE INVENTION In accordance with the invention a fixturefor heat treating furnaces is provided, with a plurality of supportlevels for work pieces, which is assembled from bars and rods and wire,of relatively low fixture mass, x

preferably of low specific heat and high temperature strength materials,such as molybdenum, tungsten, tantalum, or columbium and their alloys,or which may be of graphite, and which are not subject to eutecticformation during clean up, certain of the rods carrying ceramic tubes tosupport the work pieces.

It is the principal object of the present invention to provide a fixturefor heat treating furnaces with which the cycle time is greatly reducedby reason of the low fixture mass and low specific heat of the materialand which will have a longer life than that of fixtures heretoforeavailable.

It is a further object of the present invention to provide a fixture forheat treating furnaces which, by reason of its decreased weight ascompared with those heretofore available, makes for greater ease ofhandlin g for introduction into the furnace and for removal.

Other objects and advantageous features of the fixture will be apparentfrom the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic featuresof the invention will be more readily understood from the followingdescription taken in connection with the accompanying drawings formingpart thereof, in which:

FIG. 1 is a view in perspective of a fixture for heat treating furnacesin accordance with the invention;

FIG. 2 is a vertical sectional view taken approximately on the line 22of FIG. 1;

FIG. 3 is a fragmentary vertical sectional view, enlarged, takenapproximately on the line 3-3 of FIG. 2;

FIG. 4 is an exploded perspective view showing a preferred mode ofjoining bars and a rod for assembly of the fixture, and

FIG. 5 is a fragmentary perspective view showing the mounting of a workcarrying ceramic'tube on one of the rods.

It should, of course, be understood that the description and drawingsherein are illustrative merely and that various modifications andchanges can be made in the structure disclosed without departing fromthe spirit of the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularlyto the drawings in which a preferred embodiment of the invention isshown the fixture 10 has opposite end and side walls with a plurality ofhorizontal shelves, the fixture being detachably assembled from bars,rods, tubes and wire loops.

The fixture 10 includes vertical corner upright bars 1 1, verticalintermediate end wall upright bars 12, vertical intermediate side wallupright bars 13, and a central upright bar 14.

The corner uprights 11 are secured together by spaced horizontaltransverse rods 15, with looped wires 16 extending through openings 17and engaged therewith, the rods 15 extending through the intermediateend wall uprights 12. The intermediate uprights l2 and rods 15 are heldagainst relative movement by looped pins or wires 16.

The comer uprights 11 are held together to provide opposite side wallsby longitudinal horizontal side bars 18 through which the rods 15extend, the bars 18 being held by looped wires 16 at each end.

The oppositely disposed intermediate uprights 12 are connected bylongitudinal horizontal bars 20 carried on the rods 15 and held againstmovement by looped wires 16.

Alternate bars 20 can be disposed on opposite sides of the verticaluprights 12. I

The intermediate side wall bars20 are connected by rods 21, similar tothe rods 15, which extend through the central upright bar 14. Wire loops16, as before, prevent relative movement of the rods 21 with respect tothe side wall bars 20 and the upright bars 14.

The lowermost horizontal bars 18 preferably have horizontal transverserods 22 extending therethrough and held against displacement by loopedwires 16.

The side walls have opposite diagonal brace bars 23 and 24 extendingrespectively from an uppermost rod 15 at one end to a lowermost rod 15at the other end. The brace bars 23 and 24 are held on the rods 15 andagainst the corner bars 11 and side wall bars 13 by looped wires 16.

The bars l1, 12, 13, 14, 18, 20, 23, and 24 in the specific embodimentillustrated are preferably rectangular bars Aiinch by l liinch or 1 7%inch and the rods 15 can be of inch to /8 inch diameter, dependent uponthe loading. The bars, rods and the looped wires 16 are preferably ofrefractory metals such as molybdenum, tungsten, tantalum, columbium andtheir alloys and the bars and rods can also be of graphite.

The frame 10 as heretofore described can be readily assembled fromindividual components and can be disassembled in whole or in part asdesired by removal of the looped wires 16, for storage or forreplacement of components.

both these characteristics contributing to reduction of 5 furnace cycletime and consequent savings. The freedom from distortion and sagminimize replacement costs.

The frame as described can withstand temperatures up to 3000F and canremain in the furnace during bake-out and clean-up.

While the frame 10 as heretofore described can be used for some purposesit is preferred to employ a rack 25 composed of horizontallytransversely disposed end bars 26 in upright arrangement, connected by aplurality of horizontal rods 27 and held by wires 16 as before and whichat the center can be supported directly on one of the transverse rods21. The bars 26 and rods 27 are preferably made of the same material asthat of the other bars, rods and wires. The rods 27 can, for some useshave a diameter of the order of lhinch.

The rods 27 preferably carry ceramic tubes 28 which may. have an outsidediameter of the order of yinch with a central opening of about %inch.The ceramic tubes 28 provide a support for articles to be processed attemperatures in excess of l600F and up to 3000F.

it will thus be seen that a fixture has been provided for accomplishingthe objects and purposes of the invention. We claim: 1. A fixture forheat treating furnaces comprising a frame comprising upright corner barsconnected to horizontal transverse end rods and horizontal longitudinalside bars, and a rack comprising horizontal end bars and longitudinalrods supported by said frame,

said frame and said rack being of refractory material, said rack rodscarrying ceramic tubes for work piece engagement. 2. A fixture asdefined in claim 1 in which the connections between said bars and rodsare detachable. 3. A fixture as defined in claim 2 in which theconnections comprise wires extending through

1. A fixture for heat treating furnaces comprising a frame comprisingupright corner bars connected to horizontal transverse end rods andhorizontal longitudinal side bars, and a rack comprising horizontal endbars and longitudinal rods supported by said frame, said frame and saidrack being of refractory material, said rack rods carrying ceramic tubesfor work piece engagement.
 2. A fixture as defined in claim 1 in whichthe connections between said bars and rods are detachable.
 3. A fixtureas defined in claim 2 in which the connections comprise wires extendingthrough said rods and engaging contiguous bars.
 4. A fixture as definedin claim 1 in which said rods and said bars are of a material selectedfrom the group consisting of molybdenum, tungsten, tantalum, columbiumand their alloys and graphite.
 5. A fixture as defined in claim 1 inwhich said rods and said bars are of molybdenum.